CA2049492A1 - Resin composition - Google Patents

Abstract

Abstract A resinous composition particularly suited for forming the surface layer of a composite which includes an underlying layer of PVC or other structural plastic, the surface layer being characterized by excellent weathering properties.

Description

Field of the Invention This application is a continuation-in-part of United States patent application serial number 07/575,237 filed August 30, 1990.
This invention relates to a resin composition which can be used as capstock and in other applications. More particularly, this invention relates to a resin composition which is especially useful as a material for c oextrusion over or 5 lamination to a structural plastic such as poly(vinyl chloride), as well as to the manufacture of such composites and to the articles produced therefrom.
The present invention will be described initially in connection with its applicability to the production of a composite comprising a ply of surfacing material adhered to a ply of poly(vinyl chloride) structural plastic. The invention has wider 0 applicability, as described hereinbelow.
It is known that poly(vinyl chloride) resin (hereafter "PVC") has a combination of properties which make it particularly suitable for use as a structural material. In applications in which irnpact strength of the structural plastic isimportant, the PVC can be formulated with impact-modifier resins which improve lS the impact strength of the resulting composition. Such high impact-strength PVC
compositions can be readily extruded or otherwise formed into a variety of articles which have excellent impact strength, toughness and other desired mechanical andchemical properties. Examples of such articles are siding for buildings, particularly residential buildings, shutters, technical profiles for window and door frames, rain - carrying systems, and fencings.
A shortcoming of such PVC compositions is that they have relatively poor weatherability characteristics, particularly poor color retention in darker grade colors such as, for example, browns and blues. By way of background, it is noted that colored PVC compositions are used widely for aesthetic purposes, the color bein~imparted to the PVC composition by the use of colorants such as pigments and/or dyes. Unfortunately, exposure to sunlight causes changes in the colors - changeswhich are aesthetically unappealing. The changes are more severe for darker colors than for light colors such as whites and pastels.

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In an effort to overcome or alleviate this undesirable condition, it is known to incorporate into the PVC composition stabilizing additives, for example UV
absorbers, thermal stabilizers, titanium dioxide and the like. Although improvements are reali~ed by this approach to the problem, the improvements are not sufficiently significant to meet industry-wide standards.
Another approach to the problem is to apply another resinous material over the PVC structural plastic to provide a surface that can withstand the adverse effects caused by sunlight and other environmental conditions. Such a surfacing materialis called "capstock". The capstock generally is much thinner than the structuralplastic, typically being about I0 to about 25% of the total thic~cness of the composite comprising the capstock and structural plastic plies. For example, the thickness of the capstock can be about 0.2 to about 2.5 mm, whereas the thickness of the . structural plastic ply can be about 0.75 to about 10 mm.
A composite comprising a ply of resinous capstock and a ply of underlying PVC structural plastic can be formed in several different ways. For example, preformed sheets or films of the PVC structural plastic and the capstock can be laminated together, either by thermal fusion or via an appropriate adhesive.
Alternatively, in appropriate cases, the PVC structural plastic and resin capstock can be coextruded, with feedblock coextrusion often being a choice method for forming a sheet of the composite. The sheet of composite can then be thermoformed into an article such as, for exarnple, siding and shutters. Alternatively, multi-manifold dies can be used for forming coextruded technical profiles which can be subsequently cut and welded to produce frames for windows, doors and the like.
It should be appreciated that the resinous material comprising the capstock must have a combination of properties, including processing properties and other~5 physical, chemical, and aesthetic properties, for it to be a suitable material for capstock. To maintain the utility of PVC structural plastic effectively, it must have not only exceptional weathering characteristics, including excellent color retention, .
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but it also must not affect adversely those properties which make PVC such a widely used building material.
The present invention relates to a resin composition which is particularly suitable for use as capstock for PVC and other types of structural plastic.

Prior Art S Various types of resinous compositions have been disclosed for use as capstock, including PVC-based compositions and acrylic resin-based compositions.U.S. Patent No. 4,169,180 discloses a composite comprising an underlying ply made from a resin, such as PVC, which tends to be affected adversely by outdoor exposure and a protective surface ply comprising a resin prepared by sequential lo polymerization and comprising a crosslinked acrylate and/or methacrylate segment, a crosslinked styrene-acrylonitrile segment, and an uncrosslinked styrene-acrylonitrile segment.
U.S. Patent No. 4,183,777 discloses a PVC-based capstock for PVC structural plastic. The capstock comprises a major amount of a vinyl chloride polymer and l~i, minor amounts of titanium dioxide and a plasticizer, for example, a phthalate plasticizer.
U.S. Patent No. 4,229,549 discloses a resin composition which is described as having excellent weathering durability and excellent impact strength. The composition comprises 70 to 97 wt.~o of a rigid thermoplastic resin such as PVC and 3 to 30 wt.% of an elastic alkyl acrylate copolymer prepared from 60 to 99.5 wt.% of an alkyl acrylate, 0.1 to 10 wt.% of a polyfunctional monomer having one or moreconjugated double bonds and one or more non~conjugated double bonds and, optionally, up to 35 wt.% of a comonorner. Examples of the latter two monomers are octatrienes and 1,3-butadienes respectively. The resin composition is recommended for use as the outer layer of a multi-layer molded product.

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U.S. Patent No. 4,511,695 also discloses an acrylic resin-based graft copolymer which can be used as capstock which is said to have increased resistance to aging and better resistance to chemical solvents. This patent refers to laminates prepared from a film of the aforementioned copolymer laminated to a layer of a material comprising an ABS-PVC mixture.
Capstocks formed from the aforementioned resinous compositions generally 5 have poor ~veather resistance with regard to initial color retention. Another disadvantage associated with some prior art compositions relates to reprocessing of trimmings and the like for the purpose of conserving material and realizing economies. Resinous compositions comprising capstocks of some prior art exhibit poor miscibility ~vith resinous compositions comprising the structural plastic ply of O the composite~ This makes it difficult to recycle and re-use trimmings and the like.
The present invention relates to the provision of a resin composition which can be employed as capstock for PVC and other structural plastics and which has a combination of desired properties, especially weather-resistant and impact-resistant properties.

Summary of the Invention In accordance with the present invention, there is provided a resinous composition comprising:
(A) from about 20 to about 50 wt.% of poly~vinyl chloride) resin (PVC); and either (B) from about 50 to about 75 wt.% of a plurality of multi-Iayered, sequentially-produced, acrylic resin-based polymeric particles having an elastomeric crosslinked core sheathed by a plurality of polymeric shells, a resin portion thereof being dissociated therefrom, ~5 the dissociated portion of resin being compatible or miscible with said PVC; or :

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(C-1~ from about 17 to about 38 wt."/o of a thermoplastic resin (other than said PVC) which has weathering properties and is compatible or miscible with said PVC; and either (C-2) from about 12 to about 33 wt.% of an acrylate-based, hard core, impact-modifier resin in the form of discrete particles; or (C-3) from about 12 to about 33 wt.% of an acrylate-based, non-dissociable, soft core, impact-modifier resin in the form of discrete particles;
wherein the resins (as present) of (A) and (C-1) above and the dissociated portion of resin of (B) above constitute a continuous phase of said composition in which are dispersed (as present) the residual particles of (B) above and the resin particles of (C-2) and (C-3) above.
In preferred form, the P~IC constituent of the composition of the present invention comprises a homopolymer of vinyl chloride, particularly a homopolymer having a Fikentscher K-value of from about 62 to about 70, most preferably from about 66 to about 69 and the thermoplastic resin (C-1) has a molecular weight of at least about 80,000 daltons and is either a methyl methacrylate resin or a copolymer of methyl methacrylate and a Cl to C4 alkyl acryla~e. In particularly preferred form, the (C-1) constituent comprises a copolymer prepared by polymerizing a major amount of methyl methacrylate with a minor amount of lower alkyl acrylate, most preferably ethyl acrylate, with the molecular weight of the copolymer being from~i~ about 80,000 to about 130,000 daltons or higher, more preferably, from about 90,000 to about 120,000 daltons.
As used herein, the term "molecular weight" means weight average molecular weight. Molecular weight is estimated by conventional gel permeation chromatographic methods, using poly (methyl methacrylate) standards for calibration. The term "dalton" means atomic mass unit.

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In preferred form, the acrylic resin-based polymer cons~ituent (B) comprises a resin of the type described in U.S. Patent No. 4,141,935 and the acrylate-based, hard core, impact-modifier resin constituent (C-2) comprises multi-layered resin particles of the type described in U.S. Patent No. 3,793,402.
Other aspects of the present invention comprise capstock formed from the composition of the present invention and also other articles formed therefrom, 5 including, for example, sheets, films, and a plastic composite formed from the composition of this invention and overlying and integrally bonded to an underlying structural plastic ply, especially a ply formed from PVC.
Still another aspect of this invention comprises a method for forming a plastic composite comprising a surfacing material formed from a composition of the l0 present invention and an underlying plastic material, particularly PVC. The preferred method for forming the plastic composite is by the use of feedblock - coextrusion when a sheet or sheet-like product is desired. For the production of a technical profile having a complex shape, the technique of multi-manifold die coextrusion is preferred.
Articles formed from the improved composition of the present invention have excellent weather-resistant characteristics, including color retention. And `
excellent color retention is achieved in compositions formulated from light-colored colorants or from dark-colored colorants. Other advantages which are afforded bythe present invention are improved economics, improved flame-resistant characteristics, and improved re-processability. In connection with improved reprocessability, the composition of the invention exhibits good compatability when combined with plastic materials comprising the composite and/or with the material comprising the structural plastic ply in recycling techniques which involve regrinding of such materials and re-extrusion.
~5 The invention will be more readily understood by reference to the following detailed description.
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2 ~ 2 Detailed Description An essential ingredient of the composition of the present invention is PVC
which comprises a continuous phase of the composition and is sometimes referred to herein as a "matrix resin". For use in the practice of this invention, the PVC
constituent is a thermoplastic homopolymer or copolymer of vinyl chloride of the5 type widely utilized in the production of plastic articles. The term "poly(vinyl chloride) resin" or "PVC", as used herein, means chlorinated PVC or a homopolymer or copolymer of vinyl chloride which has vinyl chloride as the major(greater than 50 ~,vt.%) component. Thus, the PVC constituent can be a homopolymer of poly~vinyl chloride) or a copolymer of vinyl chloride and one or lo more other monomers, for example, vinyl acetate and the like, vinylidene halides such as vinylidene chloride, alkyl esters of carboxylic acids such as acrylic acid, ethyl acrylate, 2-ethylhexyl acrylate and the like, unsaturated hydrocarbons such as ethylene, propylene, isobutylene and the like, allyl compounds such as allyl acetate and the like. In the use of a copolymer of vinyl chloride, it is preferred that the l~i, vinyl chloride content comprise at least about 80 wt.% of the copolymer. The PVC
constituent can comprise a mixture of a homopolymer and one or more copolymers of vinyl chloride and/or a chlorinated PVC or a mixture of two or more copolymers of vinyl chloride and/or a chlorinated PVC.
The molecular weight and molecular weight distribution of the PVC can vary over a wide range. In applications involving extruded construction products, it is preferred that the PVC have a Fikentscher K-value of from about 62 to about 70, most preferably from about 66 to about 69. The Fikentscher K-value is determinedby the formula Lg~lrel/C = ( 7~; X 10~K~ 1.5 ~ 1~3KC ) ~5 where C is 0.5 g/100 ml concentration of polymer in solvent, [rl ] rel is relative viscosity in cyclohexanone at 25C, and K is Fikentscher value.

In preferred form, the PVC constituent is a homopolymer of vinyl chloride.
As mentioned above, the present invention comprises: in one embodiment, a composition which includes, as essential ingredients, PVC and particles of a multi-layered, sequentially-produced, acrylic resin-based polymer having an elastomeric crosslinked core sheathed by a plurality of polymeric shells, an outer portion of which is capable of dissociating from the particle (also referred to herein as 5 "dissociable soft core modifier"); and, in second and third embodiments, compositions which include, as essential ingredients, a mixture of at least two matrix resins, namely, PVC, and a thermoplastic resin which has weathering properties and which is compatible or miscible with PVC, and either an acrylate-based, hard core, impact modifier resin or an acrylate-based, non-dissociable, soft 10 core, impact modifier resin (also referred to herein respectively as "hard core modifier" and "non-dissociable soft core modifier"). The former composition is - referred to herein as "PVC/dissociable soft core composition" and the latter compositions are referred to herein respectively as "PVC/hard core composition"
and "PVC/non-dissociable soft core composition". These compositions are lS described in detail hereinafter.

PVC/Dissociable Soft Core Composition As mentioned above, the composition of this embodiment comprises a dissociable soft core modifier and PVC, the PVC constituent being a resin of the type described hereinabove.
The nature of the dissociable, soft-core modifier is such that it imparts to thePVC-based composition improved weatherability characteristics, as well as improved impact strength. An examplary dissociable, soft-core modifier which is capable of imparting this combination of properties to the PVC-based composition~5 comprises a copolymer particle having an elastomeric crosslinked core sheathed by a plurality of polymeric shells, a portion of which has the ability to dissociate from the particle. As described in more detail below, portions of such particles ha~e thecapability of dissociating under melt processing conditions, with the outer shell portion separating from the inner portion which retains its form as a ciscretc .

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particle. A preferred class of such resins for use in the present invention is described in the aforementioned '935 patent, the disclosure of which is incorporated herein by reference.
The resins disclosed in the '935 patent comprise acrylic resin-based copolymer particles having an elastomeric cross-linked core sheathed by three increasinglyharder thermoplastic copolymer shells. Such resins are multiple stage, sequentially 5 produced polymers, that is, polymers which are prepared in aqueous dispersion or emulsion and which are polymerized in the presence of a preformed latex preparedfrom a prior monomeric charge and in which each succeeding stage of polymer is attached to or intimately associated with that of its preceding stage. The resincomprises:
(A) a first elastomeric, relatively soft first-stage polymer polymerized from anaqueous emulsified monomeric system containing: (1) from about 75 to about 99.8 - ~vt.%, preferably from about 94 to about 99.8 wt.%, of a least one C2 to C8 alkyl acrylate; (2) from about 0.1 to about 5 wt.%, preferably from about 0.25 to about 1.5 wt.%, of at least one crosslinking polyethylenically unsaturated monomer; and (3) 15 from about 0.1 to about 1 wto% of at least one graftlinking polyethylenicallyunsaturated monomer; and (4) the balance, to total 100 wt.% of the first-stage monomeric system, comprising one or more copolymerizable monoethylenically unsaturated monomers, with the monomeric system being chosen so that the ma~cimum glass transition temperature is not over -20C;
(B) a second-stage polymer polymerized, in the presence of the resultant aqueous system from the first-stage polymerization, from an aqueous emulsified monomeric system containing: (5) from about 10 to about 90 wt.% of at least one C2 to Cg alkyl acrylate; (6) from about 9 to about 89.9 wt.% of at least one C1 to C4 alkyl methacrylate; and (7) from about 0.1 to about 1 wt.% of at least one graftlinking polyethylenically unsaturated monomer;
(C) a third-stage polymer polymerized, in the presence of the resultant aqueous system from the second-stage polymer, from an aqueous emulsiQed monomeric system containing: (8) from about 5 to about 40 wt.~o of at least one C2 .
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to Cg alkyl acrylate; and (9) from about 60 to about 95 wt.% of at least one Cl to C4 alkyl methacrylate; and (D) a final fourth-stage polymer having a glass transition temperature of at least 60C polymerized, in the presence of the resultant aqueous system from thethird-stage polymerization, from an aqueous emulsified monomeric system containing: (10) from about 80 to about 100 wt.% of at least one C1 to C4 alkyl 5 methacrylate; and (11) the balance, to total 100 wt.% of the fourth-stage monomeric system, of at least one Cl to C8 alkyl acrylate.
The term "crosslinking polyethylenically unsaturated monomer" or "crosslinking monomer", as used herein, means a copolymerizable monomer which contains at least two addition polymerizable unsaturated functional groups, lo each of which polymerize at about the same rate. The crosslinking monomers include: acrylic and methacrylic esters of polyols such as, for example, butylene diacrylate and dimethacrylate, trimethylolpropane trimethacrylate, and the like; di-and trivinyl benzene, and the like; and vinyl esters such as vinyl acrylate; and other crosslinking monomers. The alkylene diacrylates are preferred for crosslinking with 5 the alkyl acrylates of the first stage.
The term "graftlinking polyethylenically unsaturated monomer" or "graftlinking monomer", as used herein, means a copolymerizable monomer which contains at least two addition polymerizable unsaturated functional groups, each of which polymerize at substantially different rates with respect to each other.
20 Examples of graftlinking monomers suitable for use in the invention include: allyl, methallyl, and crotyl esters of ,~-unsaturated monocarboxylic and dicarboxylic acids such as, for example, allyl methacrylate and acrylate; and diallyl maleate, fumarate, and itaconate. Allyl methacrylate and acrylate are preferred.
Examples of copolymerizable monoethylenlcally unsaturated monomers 25 which can be used in the first-stage monomeric system of (A)(4) above are vinylidene chloride, vinyl chloride, acrylonitrile, vinyl esters, o-, m-, and p-methyl styrenes, -alkylstyrenes, and the like.
The first-stage polymer may comprise about 10 to about 75~0 of the total weight of the resultant four-stage polymer, with the balance being distributed evenly ~ . .
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or unevenly among the subsequent stages, and with the provision that no single subsequent stage is present in an amount less than 20% nor more than 75% of the total amount of the weight of the remaining subsequent stages.
The multiple-stage polymers typically have melt index values of from about 0.01 to about 2û, ~vith values of from about 3 to about 8 being preferred. The polymers desirably have minimum film-forming temperatures (MFT) of from 5 about 60 to about 100C. It is desirable that the average particle size of the first stage polymer be from about 500 to about dsO00 angstrom units.
There are preferred embodiments associated with the first- and fourth-stage reactions used to prepare the dissociable, soft core modifier. The first-stage reaction includes preferably from about 94 to about 99.8 wt.% of butyl acrylate, from about 0.'->5 to about 1.5 wt.% of crosslinking monomer, and from about 0.1 to about 1 wt.%
of graftlinking monomer. The fourth-stage reaction includes preferably methyl - methacrylate.
It is believed that the compositions that will be most widely used will comprise from about 20 to about 50 wt.% of PVC and from about 50 to about 75 wt.%
lS of the dissociable, soft core modifier, with preferred amounts comprising from about 38 to about 48 wt.% of PVC and from about 50 to about 60 wt.% of the modifier.
There follows an explanation (unconfirmed) of that which is believed to occur during the heat treatment of a PVC/dissociable soft core composition of the present invention and which is at least in part responsible for the excellent results ;~ which are achieved by use of this embodiment of the present invention. When the PVC/dissociable soft core composition is compounded by melt extrusion, an outer portion of the four-stage acrylic polymeric particle is believed, based on the long-recognized miscibility of poly(alkyl methacrylate) and PVC, to form with the PV~ a homogeneous alloy matrix phase which has dispersed therein, in discrete particle~5 form, the inner portion (including the core) of the particle from which the outer portion has dissociated. This alloy matrix phase which does not include any crosslinked resin comprises the "flowable" portion of the composition during rnelt processing. The fourth stage of the soft core dissociable resin particle, which is essentially ungrafted to the third stage, is available in its entirety to dissociate from .
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the inner portion of the particle under melt processing conditions and to form the PVC/acrylic alloy matrix phase. In addition, a portion (for example, about one-half) of the third stage, which is only partly grafted to the second stage, is free to separate from that stage and is thus available to be included in the alloy matrix phase. The presence of the highly-~eatherable acrylic polymer chains, separating and diluting the less-~veatherable PVC portion of the matrix, is believed to contribute 5 subs~antially to stabilizing the photochemical degradation of the PVC, resulting in the observed excellent weathering performance of the composition.
As such, the dissociable soft-core modifier can be considered as comprising a multi-layered, sequentially-produced acrylic resin-based polymer having an elastomeric cross-linked core sheathed by a plurality of polymeric shells, including 10 an outer shell portion, and in which a substantial proportion of the shell portion of the polymer, that is, at least about 20 wt.% based on the total weight of the polymer, has the ability to dissociate therefrom under melt processing conditions to form a homogeneous alloy matrix phase with PVC. Preferably, at least about 30 wt.% of the shell portion of the polymer is capable of dissociating in the aforedescribed way.
l~i Generally speaking, such dissociation will not exceed about 50 wt.% of the total ~veight of the polymer.
In preferred form, the dissociable portion of the soft core modifier is miscible~vith the PVC constituent of the matrix phase of the composition. The term "miscible" is used herein to refer to the ability of a resin such as, for example, the 2~ dissociable portion of the modifier to form with PVC a molecular mixture which is microscopically homogeneous, for example, a uniform blend that is characterized by the absence of microscopic regions or domains which are rich in the individual species of resins. Such uniform blends of resins are characterized by having a glass transition temperature which is intermediate the glass transition temperatures of 25 the individual species of resins. Thus, the glass transition temperatures of the individual species of resins are not detectable using conventional techniques such as differential scanning, calorimetry or dynamic mechanical analysis. The dissociable portion of polymeric particles of the aforementioned '935 patent are miscible with PVC.

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The present invention also includes within its scope dissociable sofl: core modifiers having a dissociable portion which is compatible with the PVC
constituent of the matrix phase of the composition. The term "compatible" is used herein to refer to the ability of a resin such as, for example, the dissociable portion of the modifier to form with PVC an intimate admixture in which the PVC and dissociable portion adhere tightly to one another in a mixture that is not 5 homogeneous in the sense that it includes microscopic regions or domains whichare rich in the individual species of resins. Such admixtures are identifiable by the fact that the glass transition temperatures of individual species of resins are detectable in the mixture using conventional techniques such as differential scanning, calorimetry or dynamic mechanical analysis.

PVC/Hard Core and Non-dissociable Soft Core Compositions - The compositions of these embodiments of the invention comprise a major amount of matrix resin (a mixture of PVC and a PVC-miscible or PVC-compatible thermoplastic resin having weathering properties) and a minor amount of either an acrylate-based, hard core, impact-modifier resin or an acrylate-based, non-dissociable, soft core, impact-modifier resin or a mixture thereof. The PVC constituent is a resin of the type described hereinabove.
The thermoplastic resin which forms, in combination with PV~, the matrix portion of the composition of the present invention can be selected from any of a v~riety of thermoplastic resins which are recognized in the art as having good weathering characteristics, that is, the resins are capable of retaining their chemical and/or physical properties when subjected to outdoor conditions which typically include exposure to: the rays of the sun; elevated temperatures of 80-90E or more;
temperatures below freezing; relatively rapid fluctuations in temperature; and to 25 rain, snow, sleet, etc. Examples of thermoplastic resins which are recognized as having particularly good weathering characteristics are alpha-methyl styrene/methacrylate resins, methacrylate/acrylate resins, methacrylate resins and poly(vinyl fluoride) resins. Examples of resins which are considered as having good weathering properties, that is, better than those of PVC, but not of the caliber of the s aforementioned resins, are styrene/methacrylate resins and styrene/acrylonitrileresins.
In addition to having good weathering characteristics, the thermoplastic resin is compatible with the PVC constituent of the matrix phase of the composition.
Preferably, the thermoplastic resin is miscible with the PVC constituent of the matrix phase of the composition. The terms ~'miscible" and "compatible" have the5 meanings set forth hereinabove in connection with the discussion of the dissociable portion of the soft core modifier. Methacrylate resins and methacrylate/acrylateresins are examples of resins which are miscible with PVC and wh;ch have excellent weathering characteristics. Styrene/methacrylate resins (including alpha-methyl styrene) and styrene/acrylonitrile resins are examples of resins which are compatible 10 with PVC, with the former being preferred over the latter because of their better combination of properties.
- The particularly preferred thermoplastic resins for use in the practice of this invention comprise polymerized methyl methacrylate or a copolymer prepared by polymerizing a major amount of methyl methacrylate and a minor amount of an l5 alkyl (Cl-C4) acrylate, preferably methyl or ethyl acrylate, and most preferably ethyl acrylate. The copolymer can comprise from about 85 to about 99.9 wt.% of the methyl methacrylate and from about 0.1 to about 15 wt.% of the alkyl acrylate.
Preferably, the alkyl acrylate content of the copolymer is from about 5 to about 15 wt~%, and most preferably from about 8 to about 13 wt.%, with the balance of thecopolymer comprising methyl methacrylate.
An increase in tl-e alkyl acrylate content of the copolymer increases the melt flow index and decreases the melt viscosity of the copolymer, as well as the resin composition of which it is a part. Minimizing the alkyl acrylate content also increases the hardness, the scratch resistance, and the resistance to attack on the ~5 capstock by chemicals.
The molecular weight of the preferred acrylic matrix resin is at least about 80,000 daltons~ It can range as high as 130,000 daltons or even higher. Preferably, the molecular weight is from about 90,000 to about 120,000, and most preferably it is from about 90,000 to about 105,000 daltons. Increasing the molecular weight of the 2 ~ !7 ~

copolymer, all else being the same, decreases the melt flow index and increases the melt viscosity of the copolymer and the resin composition of which it is a part.Increasing the molecular weight also improves the chemical resistance and tensile properties of the composition.
In general, the aforementioned acrylic copolymer is a random copolymer which is advantageously prepared via free radical-catalyzed bulk polymerization of a 5 mi~cture of the two monomers, in a continuous flow, stirred tank reactor, with an organic pero~ide to about 50~ conversion~ The polymer-monomer mixture is pumped to a devolatilizing twin-screw extruder where residual monomer is removed and other additives can be added. The technique for conducting this polymerization is described in the literature and is well known to those skilled in 10 the art. The random copolymer can be prepared also by bulk casting, or by suspension or emulsion polymerization, the latter being most preferred. The emulsion-prepared copolymer can be isolated by spray drying or coagulation, washing, and drying, or by coagulation, washing and extrusion devolatilization to pellets.
It is believed that use of the weatherable thermoplastic matrix resin in the composition functions to improve the resistance to photochemical degradation, o?~idation, and other mechanisms that contribute to the overall degradation of conventional exterior grade PVC formulations.
In addition to the weatherable thermoplastic resin, the PVC-based composition also includes either a hard core or non-dissociable soft core impactmodifier. Such modifiers are particles of acrylate-based, multi-layered resins or polymers in which the central or innermost portion of the multi-layered resin (referred to as the "core") is sheathed successively with one or more resin layers or shells. As is well known, such multi-layered resins are prepared typically by multi-5 stage polymerizations which are conducted sequentially.
It is well-known to add to PVC to improve the impact resistance thereof either hard core or non-dissociable soft core multi-layered, sequentially-produced acrylic resin-based polymers of the type for use in the present invention. Typically, such compositions comprise a continuous phase of PVC having dispersed therein 2 ~

discrete particles of lhe aforementioned-type resin. Speaking generally, PVC
compositions containing a hard core modifier have better weathering characteristics than a PVC composition which includes a non-dissociable soft core modifier, ~vhereas PVC compositions containing a non-dissociable soft core modifier have better impact resistance than those containing a hard core modifier. Both hard core and non-dissociable soft core modifiers have outer shells or layers which may be of 5 independent and varying degrees of hardness or softness (as measured by Tg), of crosslinking and/or graftlinking levels, of polymer or copolymer compositions, etc., depending on the uses and properties ultimately desired.
In terms of structure, and speaking generally, a hard core modifier typically includes a core comprising a non-elastomeric polymer or copolymer which is crosslinked and/or graftlinked and whose glass transition temperature generally is above room temperature (25C), usually above 40C. Examples of monomers used - in major amounts in the preparation of hard core polymers include styrene, alkyl styrenes, and a C1 to C4 alkyl methacrylate, with other monomers commonly used in minor amounts.
l5Speaking generally, a non-dissociable soft core rnodifier typically includes acore comprising a polymer or copolymer which may be crosslinked and/or graftlinked to confer rubber-like or elastomeric properties to the core, and whose glass transition temperature is typically at or below room temperature, more typically below 0C. Examples of monomers which are typically used in major ~mounts in the preparation of non-dissociable soft core modifiers are butadiene and other dienes; ethylene-propylene-diene combinations, butadiene-styrene, and Cl to C8 alkyl acrylates, with other monomer typically being used in minor amounts.
Speaking generally, non-dissociable soft core modifiers differ from dissociable soft core modifiers in that their layers are chemically linked one to the other, or are intertwined and locked at the interface due to crosslinking of the polymers of each layer, forming an inter-penetrating polymer network.
The hard core and non-dissociable soft core modifiers function primarily to enhance the physical properties of the composition, for example, toughness and impact resistance. The use of the modifiers also impro~les resistance to stress ~, ~vhitening and fading due to weathering. The preparation, blending and use of such resins are ~ell known.
The preferred PVC/weatherable thermoplastic resin/impact modifier composition of the present invention includes a hard core impact modifier. Such compositions typically have a better combination of properties than like compositions prepared from a non-dissociable soft core modifier.
There follows a detailed description of PVC/hard core compositions and of PVC/non-dissociable soft core compositions, including descriptions of preferred hard core and non-dissociable soft core modifiers.

PVC/Hard Core Composition The preferred type of hard core modifier for use in the practice of the present invention is described in the aforementioned '402 patent, the disclosure of which is incorporated herein by reference. As described in this patent, the modifier resin comprises multi-layered polymeric particles. Such resins, like the aforementioned dissociable soft core acrylic resins, are prepared also by multiple stage sequential l~i polymerizations.
More specifically, such multi-layered polymeric particles comprise at least three sequential stages of a non-elastomeric first stage polymer, an elastomericsecond stage polymer and a relatively hard third stage polymer, with the monomers ~co-monomers) used in preparing each stage of the resin being selected, as described in the aforementioned '402 patent, to provide stages or layers that have the aforementioned non-elastomeric, elastomeric, and hard properties. The non-elastomeric polymer formed in the first stage of polymerization has a glass transition temperature of greater than about 25C, and it is linked to an elastomeric polymer prepared in a subsequent stage from monomeric constituents such that the~5 glass transition temperature thereof is about 25C or less, preferably less than about 10C. And such elastomeric polymer is in turn linked to a polymer prepared in a subsequent stage from monomers such that the glass transition temperature of thepolymer is preferably greater than about 25C, and most preferably at least about 60C. ?

: ; ;, . -Preferred particles are those in which the core layer and the outer layer are linked by an allyl methacrylate graft-linking monomer and in which the core layer and the outer layer comprise resins which are made from the same monomer(s) that are used to prepare the preferred acrylic matrix resin of the composition, that is, homopolymers of methyl methacrylate or random copolymers of methyl methacrylate and a Cl to C4 alkyl acrylate, most preferably ethyl acrylate, and 5 optionally, a polyfunctional cross-linking monomer. When the matrix resin comprises a copolymer of methyl methacrylate and ethyl acrylate, it is highly preferred that each of the core layer and the outer layer of the particles comprise about 96 wt~% of methyl methacrylate and about 4 wt.% of ethyl acrylate, with the graft-linking monomer comprising about 1 wt%. In accordance with the teachings lo of the aforementioned '402 patent, various types of monomers can be used to prepare the intermediate layer of the particles. An exemplary intermediate layercomprises a random copolymer of butyl acrylate, styrene, and less than about 2 wt.%
of the cross-linking and graft-linking monomers.
The product of the sequential stage polymerization comprises a latex, that is, 15 an aqueous composition containing dispersed therein the multi-layered polymeric particles. The particles can be recovered from the latex by spray drying or by coagulation and drying. Spray drying can be advantageously carried out in the presence of a drying aid, for example, an acrylate-based resin which can be the same as or different from the matrix resin described herein. The "drying-aid" resin should, of course, be compatible with the other constituents of the resin composition and not affect adversely the chemical, physical, or aesthetic properties of the composition or articles made therefrom. A preferred "drying-aid" resin comprises a random copolymer of methyl methacrylate and an alkyl ~Cl to C4) acrylate which includes from about 90 to about 99.9 wt.% of the methyl methacrylate and from about 0.1 to about 10 wt.% of the acrylate, preferably ethyl acrylate. The molecular weight of the copolymer can vary over a wide range, for example, from about 95,000 to about 200,000 daltons. The molecular weight is preferably from about 95,000 to about 110,000 daltons. This resin can remain with the particles where it serves to function as a portion of the acrylic matrix resin.

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Indeed, other thermoplastic acrylic-based resins can also be included in the composition for the purpose of achieving desired effects or functioning as processing aids, for example, high molecular weight methyl methacrylate-ethyl acrylate copolymers having a molecular weight of at least about 1,000,000.
Other types of acrylate-based, hard core impact-modifier resins can be used in the composition of the present invention, either in place of the preferred resin5 described in the aforementioned '402 patent or in admixture therewith. Such resins, which function to increase the impact resistance of articles made from the ` composition, are multi-layered polymeric particles which are prepared by multiple sta~e sequential polymerization and which include a hard (non-elastomeric) core comprising preferably a major amount of a homopolymer of methyl methacrylate 10 or a copolymer of methyl methacrylate and an alkyl acrylate. Examples of such hard core, impact modifier resins are disclosed in U.S. Patent Nos. 4,052,525 and 4,433,103, Japanese Kokai 58-180514, and European Patent Application published under No.
270,865.
It is believed that the compositions that will be most widely used will ` 1~, comprise from about 2n to about 50 wt.% of PVC, and from about 17 to about 38 wt.%
? of the ~veather-resistant resin, and from about 12 to about 33 wt.% of the hard core acrylic resin, with preferred amounts comprising from about 40 to about 50 wt.% of ~` PVC, and from about 25 to about 35 wt.~o of the weather-resistant resin and from about 15 to about 25 wt.% of the hard core acrylic resin.

Non-dissociable Soft Core Composition The preferred type of non-dissociable soft core modifier for use in the practices~ of the present invention is described in U.S. Patent No. 3,808,180, the disclosure of which is incorporated herein by reference. As described in this paten~, the modifier comprises multi-layered polymeric particles. Such resins, like the aforementioned hard core resins, are prepared also by multiple stage sequential polymerizations.
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More specifically, such multi-layered polymeric particles comprise at least two layers comprising an elastomeric core chemically linked to a rigid thermoplasticlayer. Such multi-layered particles can be prepared by emulsion polymerization of the elastomer as a discrete phase comprising the core from a monomer mix of at least about 50 wt.% alkyl and/or aralkyl acrylate, from about 0.05 to about 5 wt.% of a poly-unsaturated cross-linking monomer, from about 0.05 to about 5 wt.% of a graft-5 linking comonomer, and from 0 to about 10 wt.% of a hydrophilic comonomer. Inpreferred form, the elastorneric phase monomer mix contains from about 0.1 to about 1 wt.% of a cross-linking comonomer, from about 0.1 to about 1 wt.% of a graft-Iinking comonomer, and from about 0.5 to about 5 wt.% of a hydrophilic comonomer, together with at least about 50 wt.% alkyl and/or aralkyl acrylate.
10Upon completion of the polymerization of the elasomeric phase, i.e., substantial exhaustion of the monomers in the initial polymerization mix, the rigid - thermoplastic is then formed by polymerization, in the same emulsion, of a monomer mix comprising at least about 50 wt.% of a C1 to C4 alkyl methacrylate.
The monomers which are polymerized to form the rigid thermoplastic phase of the 15 composite are added in such a fashion that substantially all the rigid phase material is formed on or at the surface of the elastomeric phase and has a minimum attachment level, as hereinafter defined, of about 20%.
In preparing the elastomeric core, there can be used alkyl esters of acrylic acid having alkyl groups of 1 to about 15 carbon atoms, preferably 1 to about 8, and most preferably 2 to 8 carbon atoms. Longer chain alkyl groups may be used. Other acrylic monomers, up to about 50 wt.%, less the other inclusions, can also be used, such as aralkyl esters of acrylic acid wherein the cyclic portion contains 5, 6 or 7 carbon atoms, with or without an additional alkyl bridge, and with the alkyl portion of the aralkyl group containing up to about 15 carbon atoms. Substituted acrylates or ~5 methacrylates inclu~ing alkylthioalkyl acrylates such as ethylthioethyl acrylate, and the like, alkoxyalkyl acrylates, such as methoxyethyl acrylate, and the like can also be used. Interpolymers with these acrylates can be based on up to about 40 wt.% of one or more other addition polymerizable monomers such as styrene, -methyl styrene, vinyl etheres, amides, and esters, vinyl and vinylidene halides, and the like.

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In more preferred formulations, the elastomeric core will be prepared from about 50 to about 80 wt.% of an alkyl acrylate, where the alkyl group contains 2 to 4 carbon atoms, more preferably 4 carbon atoms, from about 0.1 to about 10 wt.% other acrylic monomers, from about 0.1 to about 1 wt.% cross-linking monomers, from about 0.1 to about 1 wt.% graft-linking monomers, from about 0 to about 5, more preferably 0.5 to 5, wt.% hydrophilic monomer, and the balance other non-acrylic5 unsaturated monomers, more preferably styrene, -methyl styrene, and halostyrenes.
Preferred are those elastomers which have a glass temperature less than 25C.
More preferred are those elastomers having a glass temperature less than 10C, and most preferred are those elastomers having a glass temperature less than -25C. In all cases, these glass temperatures refer to the elastomeric portion of the modifier 10 only and do not include any subsequent phases or other polymers attached physically or chemically onto or into the particles of the elastomer.
- The particularly preferred elastomeric core comprises a copolymer prepared from about 50 to about 80 parts by weight alkyl acrylate monomers, wherein the alkyl group contains 1 to 8 carbon atoms, from 0 to about 40 parts by weight of other ethylenically unsaturated monomers, from about 0.05 to about 5 parts by weight of at least one polyunsaturated cross-linking monomer, from about 0.05 to about 5 parts by weight of graft-linking monomer, and from 0 to about 10 parts by weight of at'- least one hydrophilic monomer. Preferred are those acrylic elastomers wherein the ` polymer comprises from about 50 to about 100 parts by weight alkyl acrylate monomers, wherein the alkyl group contains 1 to 8 carbon atoms, from about 1 to about 20 parts by weight other acrylic monomers, from about 5 to about 20 parts by weight other ethyleneically unsaturated monomers, preferably those other ethylenically unsaturated units being aromatic, such as styrene and substituted styrene, from about 0.1 to about 1 part by weight of at least one polye~hylenically 25 unsaturated cross-linking monomer unit, from about 0.1 to about 1 part by weight of graft-linking monomer, and from about 0.5 to about 5 parts by weight of at least one hydrophilic monomer.
The acrylic elastomers include polyfunctional unsaturated monomers capable of cross-linking the elastomer, such as polyethylenically unsaturated monomers like :
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polyacrylates and polymethacrylates, and monomers capable of ionic and coordinate cross-linking such as acid groups and organic and inorganic bases and other electron donating groups co-ordinating with suitable electrophilic agents. The polyethylenically unsaturated monomers include polyacrylic and polymethacrylic esters of polyols such as butylene diacrylate and dimethacrylate, trimethylolpropane trimethacrylate, and the like, di- and trivinyl benzene, vinyl acrylate and 5 methacrylate and other cross-linking monomers.
As to the graft-linking monomers, allyl group-containing compounds are preferred, particularly allyl esters of ethylenically unsaturated acids. Most preferred are allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate, diallyl itaconate, allyl acid maleate, allyl acid fumarate, and allyl acid itaconate.
With respect to the use of hydrophilic monomers, it is preferred to utilize methacrylic compounds, particularly the amides and hydroxy alkyl es~ers of - methacrylic acid.
The rigid thermoplastic phase of the non-dissociable soft core modifier comprises acrylic polymers having a majority (e.g., 50-100%) of alkyl methacrylate 1`~ units in the polymer. The acrylic polymers have a heat distortion temperature greater than about 20C. preferably greater than about 50C.
The rigid thermoplastic portion of the particle is prepared of from about 50 to about 100 wt.% alkyl methacrylate, wherein the alkyl group contains 1 to 4, preferably 1, carbon atoms, and from 0 to about 50 wt.% of one or more acrylic comonomers such as other alkyl and aryl methacrylates, alkyl and aryl acrylates,alkyl and aryl acrylamides, substituted alkyl and aryl methacrylates and acrylates such halogen, alkoxy, alkylthio, cyanoalkyl, amino, alkylthiol esters, and othersubstitutions, and from 0 to about 40 wt.% of other unsaturated monomers, including acrylonitrile and methacrylonitrile, styrene monomers and substituted 5 styrene monomers, vinyl esters, vinyl ethers, vinyl amides, vinyl ketones, vinyl halides, vinylidene halides, and olefins. Generally, as the comonomer system chosen is softer, less is used in order to retain the rigid characteristics desired.

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-Preferred monomers which may be used to prepare the acrylic polyrners include alkyl esters of methacrylic and acrylic acids wherein the alkyl group contains 1 to 4 carbon atoms. The preferred cycloalkyl esters of methacrylic and acrylic acids have cycloalkyl group containing 4 to 14 carbon atoms.
The non-dissociable soft core modifier can be prepared by suspension or emulsion polymerization procedures utilizing a multi-stage or sequential 5 technique. In simplest form, the elastomeric phase is formed in a first stage, and the rigid thermoplastic phase is formed in a second stage. The elastomeric phase or rigid phase can also be sequentially polymerized.
Other types of acrylate-based, non-dissociable, soft core, impact-modifier resins can be used in the composition of the present invention, either in place of the 0 preferred resin described in the aforementioned '180 patent or in admixture therewith. As described hereinabove, such resins, which function to increase theimpact resistance of articles made from the composition, are also multi-layered polymeric particles which are prepared by multiple stage sequential polymerization.
Examples of such non-dissociable soft core modifiers are disclosed in U.S. Patent Nos. ~,096,202; 4,180,529; 4,508,875; and 4,730,023 and Japanese Kokai 59-~24916.
It is believed that the compositions that will be most widely used will comprise from about 20 to about 50 wt.% of PVC, from about 17 to about 38 wt.% of the weather-resistant resin, and from about 12 to about 33 wt.% of the non-dissociable soft core modifier, with preferred amollnts comprising from about 40 to ~0 about 50 wt.% of PVC, from about 25 to about 35 wt.% of the weather-resistant resin ~nd from about 15 to about 25 wt.% of the non-dissociable soft core modifier.

Description Applicable to the Several Embodiments of the Invention For some applications, it is preferable to include in the PVC/dissociable soft core composition and the PVC/hard core composition another resin which functions to still further improve the impact resistance of these compositions. For example, the use of an additional impact-resistant improver can be advantageous in applications where the total thickness of the plastic composite is relativel~ thin, for .

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example, on the order of one mm or less. For such purposes, it is preferred to use an impact modifier which is a multi-layered, sequentially-prGduced acrylic resin-based polymer having an elastomeric (soft) core and one or more outer resinous layers which have little or no tendancy to dissociate (less than about 10 wt.% dissociation, if any). A preferred non-dissociable soft-core modifier which is recommended foruse is the subject of aforementioned U.S. Patent No. 3,80~,180. Other types of acrylate-based, non-dissociable soft core modifiers, for example, as referred tohereinabove, can be used, either in place of the preferred resins described in the aforen~entioned '180 patent or in admixture therewith.
The amount of the non-dissociable soft core modifier will generally not exceed about 5 wt.% of the composition, for example, from about 1 to about 5 wt.%
0 Of the composition. Preferred amounts comprise from about 1.75 to about 3.25 wt.%.
For those applications in which the composition includes a dissociable soft -` core modifier, the compositions can be prepared conveniently from a pr~mix which includes such resin and to which there can be added subsequently the PVC
constituent and other ingredients that may be included in the composition. For the PVC/dissociable soft core composition, the pre-mix can comprise from about 90 to~bout 98 wt.% of the dissociable soft core modifier and from about 2 to about 10 wt.%
of the non-dissociable soft core modifier, with preferred amounts being respectively from about 94 to about 98 wt.% and from about 2 to about 6 wt.%. For the hard core composition, the pre-mix can comprise from about 30 to about 70 wt.% of a ~0 thermoplastic resin (other than PVC) having weathering properties, from about 20 to about 60 wt.% of the hard core modifier, and from about 1 to about 10 wt.% of the non-dissociable soft core modifier, with preferred amounts being respectively from about 55 to about 65 wt.%, from about 35 to about 45 wt.%, and from about 2 to about 5 wt.%~
Each of the embodiments of the compositions of this invention can include optional ingredients, examples bf which are: colorants, for example, dyes and pigments; lubricants; UV and thermal stabilizers; processing aids; inorganic fillers;
flatting agents; heat distortion modifiers; flame retardants; and smoke suppressants.
In general, the total amount of such optional ingredients will not exceed about 10 ' ~ .

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2 ~ 2 ~vt.% of the composition, for example, from about 4 to about 8 wt.~ of sùch ingredients .
It is believed that the compositions of the present invention will be used most ~idely as capstock in a composite in which the ply which underlies the capstock is PVC, including chlorinated PVC and homopolymers and copolymers of vinyl chloride, as described hereinabove. The capstock of the present invention can 5 be used to impart desired properties to other structural plastics, including, for example, plastics prepared from other vinyl halide polymers, acrylic resins, acrylonitrile/butadiene/styrene (ABS) resins, polystyrenes, a blend of ABS and PVC, a blend of PVC and an acrylic-imide copolymer, such as a methacrylic/glutarimide copolymer or an acrylic/maleimide copolymer;
10 polyolefins such as polypropylene; styrene/(meth)acrylic and (meth)acrylic multistage polymers; polyamides, polyamide-multistage polymer blends, such as .. polyamide/ABS; polyamide/polycarbonate blends; styrene/acrylonitrile copolymers and styrene/acrylonitrile - multistage polymer blends; ethylene/propylene/diene rubber blends with styrene/acrylonitrile copolymers or with polypropylene;
15 alpha-methylstyrene/acrylonitrile, alpha-methylstyrene/styrene/ acrylonitrile, alpha-methylstyrene/methyl methacrylate/ethyl acrylate; polycarbonate, polycarbonate-ABS blends, polycarbonate~multistage polymer blends; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate-polycarbonate blends, polybutylene terephthalate-polycarbonate blends, polybutylene terephthalate-multistage polymer blends, polybutylene terephthalate/polytetrahydrofuran, polyvinyl chloride-multistage polymer blends,polyvinyl chloride-~meth)acrylate blends, chlorinated polyvinyl chloride, acrylonitrile/(meth)acrylate-multistage polymer blends, acrylonitrile/(meth)acrylate/styrene, polycaprolactone, polyarylate, ~5 poly(meth)acrylates, polyacetal, high impact polystyrenes, styrene/maleic anhydride, styrene/maleimide, polyvinylidene fluoride, polyvinylidene fluoride-multistage polymer blends, cellulosics, polyamideimide, polyetherester, polyetheresteramideand polyetheramide, polyphenylene oxides, polysulfones. ~lends may be prepared from other polymer systems including polyphenylene sulfide, polyphenylene oxide, '; :', :
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~ Q ~ 2 polysulfone, polyphenylene oxide styrene blends, polyphenylene oxide-high impactpolystyrene blends, polyvinylidene chloride, polyvinylidene chloride/
(meth)acrylontriler polyvinylidene chloride/(meth) acryl~te, polyvinyl acetater polyetheretherketone, polyetherimide, thermoplastic polyimides, polyolefins suchas polyethylene, polypropylene, and copolyolefins, and other polymer types.
Random or block copolymers which combine the different functionalities can also 5 be used, and ternary or higher blends can be made from combinations of any of these polymer types for use as substrates with the capstocks of this invention. (In the above copolymer examples, and as used generally in the art, the slash mark ("/") is employed to indicate the copolymers so described as resulting from the copolymerization of their components. Blends and mixtures, on the other hand, 10 normally are stated as such. Also, the term "(meth)" as applied, for example, in "(meth)acrylic," is a convention widely used in the art which denotes "acrylic or - methacrylic.") Thus, a wide variety of structural plastics, typically referred to in the art as "rigid thermoplastics," may be used as an underlying layer, or substrate, with the capstocks of the invention. These structural plastics can be used singly as the 15 structural plastic with the capstocks of this invention or they also may be used more than singly or also in a blend of two or more polymers or copolymers to form a structural plastic blend. When more than one substrate layer is used, an adhesive (or "tie") layer also may be used. The polymers and structural plastics and blends may contain acrylic or (meth)acrylic/butadiene/styrene ("MBS") or ethylene/propylene/diene ("EPDM") polymer impact modifiers. They also may incorporate fillers described herein below. The capstock of the present invention also can be used as a surfacing material for foamed plastic, for example, foamed PVC
and foamed ABS.
For use as capstock, it is preferred that the composition be opaque to UV light ~5 and visible light (<520 nm). Species of compositions within the scope of thisinvention are opaque (for example, at least 95% opaque to light). As may be needed, opacifiers and/or pigments are added to the composition to render them opaque.
It should be understood that the composition of the present invention can be used in an application in which the composition is not compatible with an , ~ . , .

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underlying structural plastic material such as, for example, a polyolefin or a polystyrene. A composite of this type can be made effectively by including between the capstock and structural plastic a mutually compatible adhesive which adheresthe incompatible materials together.
The resin composition of the present invention can be extruded, molded, formed, or pressed into monolithic sheets or films, including capstock, using conventional equipment. The composition can also be formed according to conventional techniques~ Structural plastics can be capped with the aforesaid resin composition by employing standard laminatis)n or coextrusion techniques and equipment such as press lamination, bi-extrusion, and co-calendering; solution casting methods also may be used to provide laminated materials of the invention.
It is preferred to form sheet and sheet-like composites of the present invention by the use of feedbloclc coextrusion. The term "feedblock coextrusion," as used herein, refers to a process in which each of a resin supply of a first plastic material (for example, a structural plastic material) ancl a resin supply of a second plastic material (for example, a capstock material) is heated to a molten condition as 15 separated streams thereof are fed to a feedblock in which the streams are brought together in face to face surface contact to form a two-ply stream which in turn is fed to a sheet die in which the two-ply stream is spread laterally into a two-ply sheet under conditions of laminar flow, with the molten resin plies of the sheet being in face to face surface contact as they emerge from the die, the shaped two-ply sheet thereafter being cooled and solidified, the resultant corr.posite comprising each of the plies of the sheet integrally bonded to each other by the solidified resins comprising the sheet. As is known in the art, the process of feedblock coextrusion can be used to produce a sheet of more than two plies by use of a feedblock which is designed to accomodate more than two streams of resin or a feedblock which splits 25 h~o streams of resin and recombines them in multiple alternating layers.
Examples of uses for the capstock compositions of this invention include automotive applications such as decorative exterior trim, molding side trim and quarter panel trim panels, fender extensions,'louvers, rear end panels, pickup caps, rearview mirror housings, instrument knobs, snap-on and other fasteners for 2 ~3 ~ 2 interior or exterior trim, accessories for trucks, buses, campers, vans, and mass-transit vehicles, b-pillar extensions, and the like; appliances and tools such as lawn and garden implements and fencing, bathroom fixtures for mobile homes, components of pleasure boats, exterior components of mobile homes, lawn furniture such as chair and table frames, pipe and pipe end caps, luggage, shower stalls for mobile homes, toilet seats, signs, spas, air conditioner and heat pump 5 components, kitchen housewares, bead-molded picnic coolers, picnic trays and jugs, and trash cans; venetian blind components; sporting goods such as sailboards, sailboats, water skis; plumbing parts such as lavatory parts and the like; construction components, in addition to those mentioned previously, the additional componentsincluding architectural moldings, door molding, louvers, and shutters, mobile l0 home skirting, patio doors, siding accessories, window cladding, storm windowframes, skylight frames, end caps for gutters, awnings and car port roofs, and the like. This list exemplifies the types of applications and uses of the capstockedmaterials of this invention.
Optional ingredients that can be used in the composition of the present invention are color concentrates, for example, dyes and pigments, lubricants, UVstabilizers, thermal stabilizers, antioxidants, heat distortion temperature improvers, antistatic agents, matting agents, flame retardants, and processing aids. In general, the total amount of such optional ingredients will generally not exceed about 5 wt.
~o of the composition, for example, about 1 to about 5 wt. % of such ingredients. The 20 optional ingredients may be used in the capstock composition, the structural plastic, or in both. Additionally, fillers such as wood fibers, carbon fibers, and glass fibers and the like may be optionally included in the composition of the present invention, although these particular fillers would be expected to be poorly resistant to weathering. Additionally, glass beads and minerals such as calcium carbonate,25 talc, titanium dioxide, barium sulfate, and the like also may be optionally included in the composition of the present invention. In general, the total amount of such optional fillers will not exceed about 15 weight percent in the capstock and about 65 weight percent in the structural plastic or substrate.

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The following examples are illustrative of the invention.

Examples , The composition of Example 1 comprises a mixture of matrix resins and a hard core, impact-modifier resin.
Example 1-Hard Core Composition The composition of Example 1 is prepared from a mixture of three different matrix resins designated (A), (B) and (C) below.

Matrix Resins lG (A) This matrix resin is PVC, the source of which is a fully-formulated PVC composition which comprises the following constituents in the amounts indicated (parts per hundred).

Ingredients Amount, phr l~ (a) PVC, K69 100 (b) non-dissociable,soft core, 5 impact-modifier resin based on 80 wt.% butyl acrylate core and 20 ~ut.% methyl methacrylate shell (c) tin carboxylate stabilizer 3 (d) lubricant mixture-1.2 phr calcium stearate, 0.4 phr paraffin wax, 0.15 phr of polyethylene wax, & 0.6 phr of a lubricating processing aid (high molecular weight acrylic/styrene polymer) ~inyl .
acrylate resin 2.35 (e) fusion aid - high molecular weight acrylic processing aid (f) triazole UV stabilizer 0.17 - `, `'''.` ' ` ~ :

The PV~ composition described above is prepared by blending the components in a hi~h intensity mixer.
(B) This matrix resin is a random copolymer of 91 wt.% methyl methacrylate and 9 wt.% ethyl acrylate having a molecular weight of about 95,000 daltons. The copolymer is prepared in a continuous flow, stirred tank reactor in the presence of an organic peroxide.
(C) This matrix resin is a random copolymer of 91 wt.% methyl methacrylate and 9 wt.~o of ethyl acrylate having a molecular we;ght of about 100,000 daltons. The copolymer is prepared by emulsion polymerization, first by forming a seed in situ and then by forming the rest of the polymer by a reactor/batch process.
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The impact-modifier resin used in the composition of Example 1 is as follows.
.
Hard Core, Impact-~Iodifier Resin The modifier resin comprises polymeric particles having three layers and is prepared by the multiple-stage, sequential procedure described in aforementionedU.S. Patent No. 3,7~3,402. The core layer and outer layer are each composed of random copolymers of approximately 96 wt.% methyl methacrylate and 4 wt.% ethyl acrylate, with the core layer copolymer graft-linked with 0.2 wt.% allyl methacrylate.
The intermediate layer is a random copolymer of about 81 wt.% butyl acrylate and 18 wt.% styrene, graft-linked with about 1 wt.% allyl methacrylate. The proportions of the core, intermediate, and outer layers are 35%, 45%, and 20%, respectively. The modifier resin has a particle size of from about 250 to about 350 nanometers.
.
Blending of the Resin Constituents The resin constituents described above are blended in the manner described hereinbelow to provide the composition of Example-1 which contains the ~ollowingingredients in the amounts indicated.

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Composition of Example l Ingreclients w t. ~o PVC resin 44.8 MMA/EA resin (B) 25 MMA/EA resin (C) 5 hard core, impact-modifier resin 20 non-dissociable, soft core, impact-modifier resin 2.2 tin carboxylate stabilizer 1.4 lubricants 1.1 fusion aid 0.4 UV stabilizer 0.1 In preparing the composition of Example 1, a mixture of matrix resin (C) and thehard core, impact-modifier resin is prepared and then admixed with matrix resin (B). The mixture is prepared by combining 20 wt.% of a latex containing 50 wt.~o of the resin of (C) above with 80 wt.% of impact-modifier resin in a vessel equipped with a stirrer and blending to homogeneity. The blend is spray dried and isolated as a free-flowing powder. Fifty parts by weight of this mixture are mixed manually with 50 parts by weight of matrix resin (B) to provide a composition containing 50 ~vt~% of matrix resin (B), 10 wt.% of matrix resin (C) and 40 wt.% of impact-modifier resin. This composition is melt blended in a conventional extruder and extruded to pellets. The pellets are combined with the fully-formulated PVC composition in a50/50 weight ratio in a polyethylene bag where they are mixed by manual agitation.
The dryblend is then fed to a single screw extruder (25 mm diameter by 600 mm effective screw length) for melting and dispersive mixing. The barrel zones and die zone are controlled at 196C, with the melt extruded as a strand, cooled in water, and pelletized.
The next example is illustrative of a composition like that of Example 1, but containing different amounts of constituents.

2 ~ 9 2 Example 2-Hard Core Composition The composition of this example is prepared utilizing different proportions of ingredients as described hereinbelow. The composition, which is prepared in the form of pellets, comprises the following.

Composition of Example 2 Ingredients wt.%

PVC 22.4 MMA/EA matrix resin (B) 37.5 MMA/EA matrix resin (C) 7.5 hard core, impact-modifier resin 30 non-dissociable, soft core, impact-modifier resin 1.13 tin carboxylate stabilizer 0.7 lubricants 0.52 - fusion aid 0.2 UV stabilizer 0.05 The composition of Example 2 is prepared by combining the matrix-resin-containing pellets and PVC composition referred to in Example 1 in a 75/25 weight ratio.

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Examples 3 8~ 4-Hard Core Compositions The next two examples are illustrative of compositions similar to those of Examples 1 and 2, but containing only one type of acrylic resin as a matrix resin, that is, resin (C) above. The compositions comprise the following.

Amts, wt.%-Comps. of Ingredients Ex. 3 Ex.4 PVC 44.8 22.4 MMA/EA matrix resin (C) 30 45 hard core, impact-modifier resin 20 30 non-dissociable, soft core, impact-modifier resin 2.2 1.13 tin carboxylate s~abilizer 1.4 0.7 lubricants 1.1 0.52 fusion aid 0.4 0.2 ` UV stabilizer 0.1 0.05 The composition of Example 3 is prepared by blending 60 parts by weight of the 15 MMA/EA type latex referred to in Example 1 with 40 parts by weight of the hard.
core, impact-modifier resin (the source thereof also a latex). The resulting homogeneous blend is then spray dried. Fifty parts by weight of the resulting resin powders are combined with 50 parts by weight of the PVC composition and then formed into pellets as described in Example 1. The composition of Example 4 is prepared in the same way as that of Example 3 except that 75 parts by weight of the resin powders are combined with 25 parts by weight of the PVC composition.
The next example is illustrative of a composition of the present invention in ~hich there is used a soft core impact-modifier resin.
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Example 5-l~issociable soft Core Comyosition The composition of this example includes a dissociable, soft core resin like that described in Example 1 of aforementioned U.S. Patent No. 4,141,935. The resin, as described in the patent, is prepared from the following constituents in the amounts indicated in a four-stage sequential polymerization: first stage - 25[butyl acrylate (BA)/1,3-butylene glycol diacrylate (BDA)/allyl methacrylate (ALMA) -98~5/1~0/0.5]; second stage- 25[BA/methacrylic acid (MA)/ALMA-40/60/0.5]; third stage - 25[methyl methacrylate (MMA)/BA/n-dodecyl mercaptan (n-DDM) -~0/10/0~5]; fourth stage - ~5 [MMA/BA/n-DDM) - 90/10/1.5]. The resin is recovered in the form of a latex having a solids content of about 45 wt.%.
The composition of Example 5 comprises the following.
Ingredients wt.%
.. PVC 44.8 dissociable, soft core modifier resin 50 soft core, impact-modifier resin 2.2 tin carboxylate stabilizer 1.4 lubricants 1.1 lS fusion aid 0.4 UV stabilizer 0~1 The composition of Example 5 is prepared by combining the dissociable, soft core, modifier resin with the fully-formulated PVC composition described above in a 50/50 weight ratio in a polyethylene bag and mixing by manual agitation~ This ~ dryblend is then fed to a single screw extruder (25 mm diameter by 600 mm effective screw !ength) for melting and dispersive mixing. The barrel zones and die zone are controlled at 180C, with the melt extruded as a strand, cooled in water, and pelletized.
~s To each of the compositions of Examples 1 to 5 is added a brown concentrate comprising 21.8 wt.% of brown pigment (Chromophthal 5R of Ciba Geigy Co~), 7~2 wt.% of violet dyes, and 71 wt~% of an acrylate resin dispersion aid~ The concentrate is added on the basis of 4 parts by weight of concentrate per 100 parts by weight of each of the compositions of Examples 1 to 5. The resulting compositions are used as , - ',, '' 2 ~ 2 capstocks over PVC resin substrates, each of which is composed of the following ingredients.

In redients of PVC Structural Plastic Amounts, phr PVC, K69 ((~eon 103EPF76) 100 non-dissociable soft core, impact-modifier resin (Kl~/I-334 of Rohm and Haas Co.) 5 TiO~ pigment 4 CaCO3 filler 5 lubricant mixture-1.9 phr calcium stearate, 1.3 phr paraffin wax, & 0.3 phr of vinyl acrylate resin 3.5 tin mercaptide stabilizer 1.1 acrylic processing-aid resin 0.5 The composition described above is prepared by blending the ingredients in a high intensity mixer.
Composites are formed from the PVC structural plastic composition and the lS capstock compositions of Examples 1 to 5 utilizing conventional feedblock coextrusion. Appropriate charges are made to the hoppers of separate extruders.
The extruder for the PVC structural plastic composition is a 25 mm conical counter-rotating twin screw extruder. The extruder for the capstock compositions is a 25mm single screw extruder. Convergence of the melt streams is effected by a ~0 feedblock that has a 3.2 mm by 3.2 mm orifice vertically centered over the melt ~tream from the extruder for the structural plastic composition in the die, through which the capstock composition flows and distributes into a 4"-wide composite ~vhich is then air cooled and cut to length for testing.

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The feedblock temperature is 160-177C and the die temperature 177-193C.
The temperatures associated with the extruder for the capstock compositions are as follows.

Barrel Temperatures, Capstock C
CompositionMelt Temp., C Zone 1 Zone 2 Zone 3 Exs~ 1, 2, 3 & 4 205 188 189 193 Ex. 5 196 177 182 188 The extruded composites had capstock thicknesses of about 5 to about 10 mils (0.125 to 0 25 mm) and the thicknesses of the PVC structural plastic plies are from about 30 to about 35 mils (0.76 to 0.90 mm), with the composites being from about 40 to about 45 mil (1.0 to 1.14 mm) in total thickness. Such composites are typical of materials used in the residential siding industry.
Table 1 below shows the impact strengths of unembossed samples of the composites of the capstock/PVC substrates for those composites made from the 5 capstock compositions of Examples 1, 2 and 5.

Table 1 Capstock Impact (ASTM D 4226A-85), Composition _ Toules/mm ~ Ex. 1 13.5 (sigma 0.5) Ex. 2 9.8 (sigma 1.5) Ex. 2 (second sample) 10.5 (sigma 2.2) Ex. 5 13.4 (sigma 1.6) The industry standard for residential siding is a minimum of 8.9 Joules/mm (unembossed). PVC substrates (without capstock) yield values typically in the range of about 10 to 14 Joules per millimeter thickness. Thus, it can be seen that theimpact strengths of the composites are satisfactory for their intended use and, in fact, are not affected adversely by the capstock.

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Table 2 below shows characteristics of color retention for composites prepared in accordance with this invention utilizing the capstock compositions identified in Table 2. Co-extruded capstock/PVC substrate composites are tested by the Xenon Arc/Weathering Test methods described in ASTM Method G 26, Method ~, utilizing a BH-type apparatus. The irradiating source uses Type S borosilicate filters ~inner and outer) set for 0.35 W/square meter with the wavelength band at 340 5 nanometers. The black panel temperature is set at 63C; cycle is 102 minutes of light, 18 minutes of light plus water spray (16 deg.C, +/- 5 C deg.); the clry cycle is set at 50%
relative humidity~ Differences in total ~unter color change (Delta E) are calculated by the procedures of ASTM Method D 2244 using an integrating sphere colorin eter~Hunter D25-9). Test samples are evaluated with the specular component excluded.
Table 2 Change in Total Color (Delta E) in Xenon Arc, with Weathering Capstock Composition (ASTM G 26), after Hours Stated E~c. 1 1.15 2.9 3.9 5.8 Ex. 2 0.75 1.7 2.7 5.5 Ex. 5 0.74 1.9 2.5 2.8 2~
PVC-based and other capstock materials such as resins based on styrene/acrylonitrile (SAN) polymers or copolymers, SAN-grafted polymers or copolymers, and blends of the aforementioned SAN polymers with other polymers typically have Delta E
values of from about 2 to about 3 after 2000 hrs. and from about 4 to about 11 after 4000 hrs., and from about 4 to about 11 after 5000 hrs.
In summary, it can be said that the present invention provides a composition which is capable of being used effectively as capstock having excellent properties, including particularly, excellent weather-resistant properties.

Claims (35)

1. A resinous composition comprising:
(A) from about 20 to about 50 wt.% of poly(vinyl chloride) resin (PVC); and either (B) from about 50 to about 75 wt.% of a plurality of multi-layered, sequentially-produced, acrylic resin-based polymeric particles having an elastomeric crosslinked core sheathed by a plurality of polymeric shells, a resin portion thereof being dissociated therefrom, the dissociated portion of resin being compatible or miscible with said PVC; or (C-1) from about 17 to about 38 wt.% of a thermoplastic resin (other than said PVC) which has weathering properties and is compatible or miscible with said PVC; and either (C-2) from about 12 to about 33 wt.% of an acrylate-based, hard core, impact-modifier resin in the form of discrete particles; or (C-3) from about 12 to about 33 wt.% of an acrylate-based, non-dissociable, soft core, impact-modifier resin in the form of discrete particles;
wherein the resins (as present) of (A) and (C-1) above and the dissociated portion of resin of (B) above constitute a continuous phase of said composition in which are dispersed (as present) the residual particles of (B) above and the resin particles of (C-

2) and (C-3) above.
2. The composition of Claim 1 wherein the thermoplastic resin is miscible with said PVC and has a molecular weight of at least about 80,000 daltons and consists essentially of a methyl methacrylate resin or a copolymer of methyl methacrylate and a C1 to C4 alkyl acrylate.

3. The composition of Claim 2 including the polymeric particles of (B) above.

4. The composition of Claim 3 including also from about 1 to about 5 wt.% of a non-dissociable soft core, impact-modifier acrylic resin.

5. The composition of Claim 2 including the resins of (C-1) and (C-2) above.

6. The composition of Claim 5 including also from about 1 to about 5 wt.% of a non-dissociable soft core, impact-modifier acrylic resin.

7. The composition of Claim 2 including the resins of (C-1) and (C-3) above.

8. The composition of Claim 5 wherein the thermoplastic resin consists essentially of a copolymer of from about 0.1 to about 15 wt.% of said alkyl acrylate and from about 85 to about 99.9 wt.% of said methyl methacrylate.

9. The composition of Claim 8 including from about 8 to about 13 wt.% of alkyl acrylate and from about 87 to about 92 wt.% of methyl methacrylate.

10. The composition of Claim 9 wherein the alkyl acrylate is ethyl acrylate.

11. The composition of Claim 8 wherein the molecular weight is from about 80,000 to about 130,000 daltons.

12. The composition of Claim 5 or 6 wherein the modifier resin (C-2) comprises multi-layered polymeric particles having an intermediate layer sandwiched between a core layer and an outer layer, the core layer being a non-elastomeric polymer, the intermediate layer being an elastomeric polymer, and the outer layer being a hard polymer.

13. The composition of Claim 12 wherein each of the core and outer layers comprises random copolymers of methyl methacrylate and ethyl acrylate and the intermediate layer comprises a random copolymer of butyl acrylate and styrene.

14. The composition of Claim 2 wherein the polymeric particles of (B) have an elastomeric cross-linked core sheathed by a plurality of polymeric shells, including an outer shell, and in which at least about 20 wt.% of the shell portion of the resin has the ability to dissociate therefrom under melt process conditions to form a homogeneous alloy matrix phase with the PVC.

15. The composition of Claim 14 wherein at least about 30 wt.% of said shell portion has the ability to dissociate.

16. A composition for use in preparing the composition of Claim 4 comprising from about 90 to about 98 wt.% of the polymer of (B) and from about 2 to about 10 wt.% of the impact-modifier acrylic resin.

17. A composition for use in preparing the composition of Claim 6 comprising from about 30 to about 70 wt.% of the thermoplastic resin (other thanPVC) having weathering properties, from about 20 to about 60 wt.% of the hard core, impact-modifier resin, and from about 1 to about 10 wt.% of the soft core, impact-modifier acrylic resin.

18. A composition of Claim 1 including the polymeric particles of (s) and wherein the dissociated portion thereof is miscible with said PVC.

19. A composition of Claim 1 including a thermoplastic resin of (C-1) which is miscible with said PVC.

20. A composition of Claim 1 including a thermoplastic resin of (C-1) selected from the group consisting of alpha-methyl styrene/methacrylate resins, methacrylate/acrylate resins, and methacrylate resins.

21. A composition of Claim 1 including a thermoplastic resin of (C-1) selected from the group consisting of styrene/methacrylate resins and styrene/acrylonitrile resins.

22. A composition of Claim 2 wherein said PVC is a homopolymer of vinyl chloride.

23. Capstock made from the composition of Claim 1, 2 or 14.

24. Capstock of Claim 23 which is opaque.

25. A composite comprising a laminate in which the capstock of Claim 23 overlies PVC structural plastic and is opaque.

26. A composite comprising a laminate in which the capstock of Claim 23 overlies a structural plastic comprising chlorinated PVC, acrylic/butadiene/styrene (ABS) resin, a blend of ABS and PVC, or a blend of PVC and an acrylic-imide copolymer.

27. A composite comprising a laminate in which the capstock of Claim 23 overlies a structural plastic comprising a polyolefin which is incompatible with the material of the capstock, and including an adhesive layer disposed between the capstock and the structural plastic to adhere the two materials.

28. A composite formed by feedblock coextrusion or multi-manifold coextrusion and including a ply formed from the composition of Claim 1.

29. A composite including a ply formed from the composition of Claim 1 and in the form of residential siding, rain gutter or shutter, or window frame or door frame or other technical profile.

30. A method for forming a laminate which comprises subjecting the composition of Claim 1 and a material comprising a structural plastic to feedblock coextrusion or multi-manifold coextrusion.

31. The method of Claim 30 wherein the structural plastic is PVC.

32. An article formed from the resinous composition of claim 1.

33. An article formed from the composite of claim 25.

34. An article formed from the composite of claim 26.

35. An article formed from the method described in claim 30.